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Pixel Circuit for an Active-Matrix Organic Light-Emitting Diode Display

a technology of organic light-emitting diodes and pixel circuits, which is applied in the direction of electric variable regulation, process and machine control, instruments, etc., can solve the problems of adverse and significant effects on luminance uniformity and stability of the whole display, and the sensitive to the change of electric current, so as to increase the luminance uniformity and stability of the display

Inactive Publication Date: 2016-02-04
EVERDISPLAY OPTRONICS (SHANGHAI) CO LTD
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  • Summary
  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Benefits of technology

The present invention solves the technical problem of threshold voltage variation in an active-matrix organic light-emitting diode display by providing a pixel circuit that includes an initialization module, a signal voltage writing module, and a light-emitting display module. Additionally, the driving circuit includes a threshold voltage compensation module that uses a driving transistor and a sixth switch to precisely control the electric current flowing through the organic light-emitting diode. This results in an increased luminance uniformity and stability of the display.

Problems solved by technology

However, the AMOLED display is driven by electric current and is, thus, very sensitive to the change of electric current.
Although the a-Si processing has a high yield and the initial threshold voltages Vth are substantially the same, a drifting phenomenon, however, occurs in the threshold voltages Vth after a long period of operation, leading to a variation in the electric current.
The luminance uniformity and stability of the whole display are adversely and significantly affected.

Method used

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  • Pixel Circuit for an Active-Matrix Organic Light-Emitting Diode Display
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  • Pixel Circuit for an Active-Matrix Organic Light-Emitting Diode Display

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Embodiment Construction

[0028]The present invention will be further described in connection with the accompanying drawings and specific embodiments.

[0029]FIG. 2 is a circuitry diagram of a pixel circuit for an active-matrix organic light-emitting diode display according to the present invention including an organic light-emitting diode 20 and a driving circuit.

[0030]The organic light-emitting diode 20 includes an anode 21 and a cathode 22 electrically connected to a second power voltage BSS (namely, a negative terminal of the power).

[0031]The driving circuit includes a first switch 31, a second switch 32, a third switch 33, a fourth switch 34, a fifth switch 35, a sixth switch 36, a driving transistor 40, and a capacitor 50 having a first capacitor end 51 and a second capacitor end 52.

[0032]Each of the first, second, third, fourth, fifth, and sixth switches 31, 32, 33, 34, 35, 36 and the driving transistor 40 includes a first end 311, 321, 331, 341, 351, 361, 41, a second end 312, 322, 332, 342, 352, 362, ...

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Abstract

A pixel circuit for an active-matrix organic light-emitting diode display including an organic light-emitting diode and a driving circuit. The driving circuit includes six switches, a driving transistor, and a capacitor. By compensating the threshold voltage of the driving transistor, the electric current flowing through the organic light-emitting diode can precisely be controlled without influence by the threshold voltage of the driving transistor, increasing the luminance uniformity and stability of the display. Furthermore, the present invention can be applied to a depletion mode driving transistor (i.e., an oxide TFT). Thus, the threshold voltage can be obtained to proceed with compensation no matter the threshold voltage of the driving transistor is larger or smaller than zero.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]The present invention claims the benefit of priority to CN 201410376585.7, filed on Aug. 1, 2014 with the State Intellectual Property Office of the People's Republic of China, the specification of which is incorporated herein in its entirety by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to a pixel circuit for a display and, more particularly, to a pixel circuit for an active-matrix organic light-emitting diode display.[0003]For an active-matrix organic light-emitting diode (AMOLED) display, its pixel circuit uses a thin-film transistor as an element to turn on / off and drive the AMOLED. However, the AMOLED display is driven by electric current and is, thus, very sensitive to the change of electric current. Threshold voltage Vth variation occurs during amorphous silicon (a-Si) processing of the thin-film transistor serving as the driving element. Although the a-Si processing has a high yield and the initial thre...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G09G3/3233H05B44/00
CPCH05B33/0896G09G3/3258G09G3/3233G09G2300/0861G09G2310/0262G09G2320/045H05B45/60Y02B20/30
Inventor LU, JIAHAOMOU, XIN
Owner EVERDISPLAY OPTRONICS (SHANGHAI) CO LTD
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